CAD surfaces

[kb133]

I have done my CAD model as surfaces in Onshape. How can I connect all the individual surfaces together to form one part so that I can perform CFD on it? Thanks for your help

[psosnowski]

Hello!

Well, to get the geometry for CFD analysis, you need a “closed shape” in your CAD. As far as my experience shows, any time you close a volume with surfaces in Onshape it will create a solid Part.
You simply upload this part to SimScale and use as a flow domain / flow obstacle in your simulation.

In case of trouble do share the link to example geometry in Onshape so we all can take a look and help

Best,
Pawel

[Maciek]

Hi @kb133

Actually you don’t have to have fully closed and sealed geometry. All depends on what you do.

Here I did simple meshing test where I presented the general idea (I used surface model):

CAD issues for CFD analysis

Hi @lisandromaders I’d like to add a few words to this discussion. Well, for me such problems are nothing new and given my experience I would recommend: 1. Check geometry in your CAD program – I know, it’s obvious, but to be absolutely sure your model is clean do double check, which is: create your geometry (whatever it is) export it to .step file (or any other) reimport it by your CAD system and check if everything is ok; what’s more, import assembly as a part file (!) as in CFD we need a c…

As you can see it’s all about the gap and mesh element sizes. However, as @psosnowski wrote, it’s highly recommended to have solid geometry (!). Otherwise you ask for trouble